Dresden 2006 – scientific programme

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MA: Magnetismus

MA 35: Magnetic Thin Films V

MA 35.4: Talk

Friday, March 31, 2006, 11:30–11:45, HSZ 03

Temperature and thickness dependence of magnetic parameters in uncapped Fe monolayers on {4× 6}GaAs(001) — •Kh Zakeri, Th Kebe, J Lindner, and M Farle — Fachbereich Physik, Experimentalphysik-AG Farle,Universität Duisburg-Essen, Lotharstr. 1, 47048 Duisburg, Germany.

Epitaxial 3-20 monolayers of Fe have been grown by molecular beam epitaxy on 4×6 surface reconstructed GaAs(001) at room temperature. Both, the temperature and thickness dependence of the magnetic anisotropy and of the magnetization were determined by means of in situ Ferromagnetic Resonance (FMR) and in situ SQUID magnetometry in ultrahigh vacuum (UHV). The measured anisotropy contributions were quantitatively explained by using a magneto-elastic model considering the magneto-elastic coupling constants of the iron films on GaAs(001). The magnetization M (T—→0 K) is found to be reduced for d<7 ML. The cubic anisotropy contribution become very small for d = 5 ML , and we find that the independently measured second-order, out-of-plane uniaxial anisotropy K_2⊥(T) and the magnetization M(T) obey the Callen-Callen power law K_2⊥(T)/K_2⊥(0)∝(M(T)/M(0))^Γ with Γ= 2.9±0.2. The extrapolation of the temperature dependence (40-400 K) of the volume (K_2⊥^v) and the surface/interface (K_2⊥^s,eff) contributions to T—→0K yields K_2⊥^s,eff(T—→0) = 1.26 ± 0.1 ×10⁻³ J/m² (649 ± 51.5 µeV/atom) and K_2⊥^v(T—→0)=4±9×10⁴ J/m³(3± 6.7 µeV/atom) which can be compared to ab initio band structural calculations. Supported by DFG, SFB 491 TPA9.